1. Field of the Invention
The present invention relates in general to a V-type internal combustion and more particularly to a water pump driving arrangement for such an engine. Furthermore, the present invention relates to the layout or arrangement of a thermostat housing and an engine mounting boss portion for a V-type internal combustion engine.
2. Description of the Prior Art
A water pump for an internal combustion engine includes a pump housing which is arranged so as to cover a coolant inlet at the front end of a cylinder block. The water pump is driven by a crankshaft by way of a belt drive mechanism using a so-called V-belt. More specifically, a pulley is installed on a water pump shaft which is in turn supported on the pump housing, and the V-belt is placed around the pump shaft pulley and a crankshaft pulley.
In the case of an overhead valve engine, a camshaft or camshafts are installed on a cylinder head and driven by the crankshaft by way of timing belts or chains which are housed in a front cover at the front end of the engine. The pump housing is located more forward of the front cover and thus protrudes considerably from the front end of the cylinder block.
The pump shaft is installed on the pump housing by way of bearings.
A problem of the prior art water pump driving arrangement is that the timing chains and the V-belt are arranged in sequence in a lengthwise direction of the engine. Due to this, the crankshaft pulley and the pump shaft pulley protrude considerably forward of the engine, thus causing a problem that the length of the engine is considerably large.
Another problem is that the durability of the bearings for support of the pump shaft is poor since the distance between the water pump pulley and its adjacent bearing is large. Further, the durability of the bearings is liable to become further worse since the V-belt requires a large angle of contact with the water pump shaft pulley, causing the water pump shaft pulley to be pulled strongly in one direction.